I am going to transfer this thread to the "shell scripting" forum, as it belongs there.

If the input varies, as you say, you have to find a constant pattern to express it. If - for instance - the place where you want to insert a second space is the first place where a "3" and a "5" are separated by a blank then the expression to match this would be

Code:

sed 's/3 5/3  5/'

which would mean "search for the first occurrence of "3-space-5" and replace it with "3-space-space-5".

If, also for example, it is the space between the first two "words" in a line, than the expression would have to be:

Code:

sed 's/ /  /'

This means: search for the first occurrence of "space" and replace it by "space-space". This way "xxx-space-xxx" would become "xxx-space-space-xxx" and "xxxxxx-space-xx" would become ""xxxxxx-space-space-xx".

And so on and so forth. get a book about regular expressions and it will teach you how to do that.

I hope this helps.

bakunin